1. Riser Soil Contact

The contact model includes in addition to the sea floor contact:

  • nonlinear stiffness as the pipe is pressed into the seafloor and a separate unloading curve as the pipe is lifted

  • suction forces are activated as the pipe is lifted off the seafloor

References

Voie, P. E., Skeie, G. and Bergan-Haavik, J. (2014):Importance Rating of Riser-Soil Interaction Effects,OMAE2014

1.1. Sea floor soil properties

Available input parameters are

  • Submerged weight of the soil

  • Soil shear strength at sea bed

  • Soli shear strength vertical gradient

  • Soil Poisson ratio

  • Soil G-modulus/compressive strength

1.2. Normal contact model options

Available input parameters are

  • Relationship between dynamic stiffness and G-modulus

  • Control parameter for suction release displacement

  • Scaling factor for peak soil suction relative to peak soil compression

  • Mobilization displacement for soil bearing capacity as fraction of pipe soil contact width

  • Mobilization displacement for max soil suction as fraction of pipe soil contact width

A set of default values are specified

1.3. Sea floor in-plane contact

For sea floor normal in-plane contact in axial direction the specification consists of

  • Axial stiffness

  • Axial friction

  • Axial damping

For sea floor normal in-plane contact in lateral direction the specification consists of

  • Lateral stiffness

  • Lateral friction

  • Lateral damping